Substrate and a liquid crystal display panel capable of being cut by using a laser and a method for manufacturing the same

ABSTRACT

Disclosed is a liquid crystal display panel capable of being cut by a laser light. The liquid crystal display panel according to the present invention includes a substrate having a buffer layer between a conducting layer and an inner surface of the substrate, in which the buffer layer is disposed along a cutting line and spreads a crack and edges of the conducting layer is positioned in a region defined by the cutting line. Further, a method for manufacturing the liquid crystal display panel is disclosed, in which the liquid crystal display panel is machined by a laser cutter and a laser grinder.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display panel, andmore particularly to a structure of an upper and lower substrates of theliquid crystal display panel which is cut into an unit panel before aliquid crystal is introduced between the upper and lower substratesintegrated with each other. Further, the present invention relates to amanufacturing the liquid crystal display panel which is capable of beingcut by a laser light.

2. Description of the Prior Art

Recently, a liquid crystal display (hereinafter, referred to as a LCD)module is widely used as a display unit instead of a cathode ray tube,because of its small size, light weight, and low consumption of power.The LCD module is a plan display unit using a liquid crystal as a lightshutter transmitting and screening a transmission of the light,according to the electric signal.

A thin film transistor LCD module (hereinafter, referred to as TFT LCDmodule) is provided with a TFT substrate, a color filter substrate, anda liquid crystal introduced between the TFT substrate and the colorfilter substrate. The TFT substrate and the color filter substrate aremade of two parent glass substrates which are respectively divided intosix LCD panels.

The parent glass substrate which is used for the TFT substrate has aplurality of gate lines, a plurality of data lines which arerespectively intersected with each gate line, TFT devices respectivelyformed at each intersection of the gate lines and the data lines, andpixel electrodes.

Another parent glass substrate which is used for the color filtersubstrate includes color filter layers respectively having red, green,and blue, a black matrix, and corresponding electrodes. The black matrixprevents a mixture of light in the color filter layers and keeps thethin film transistors from operating in an off-state.

The TFT substrate and the color filter substrate as constructed aboveare arranged, assembled together and cut along a cutting line into aplurality of the LCD panels before the liquid crystal is introducedbetween the substrates.

FIGS. 1 and 2 are views showing processes of cutting the integratedsubstrate by using a diamond scriber and attaching a polarizing plate tothe substrate.

Referring to FIG. 1, a method of manufacturing an LCD panel according tothe conventional art includes a step ST1 of integrating substrates, astep ST2 of cutting the integrated parent substrates using the diamondscriber, a step ST3 of filling the liquid crystal between the integratedsubstrates, a step ST4 of sealing a liquid crystal introducing inlet ofthe integrated substrates, a step ST5 of attaching the polarizing platesto outer surfaces of the integrated substrates, a step ST6 of grinding acut surface of the substrates using a grinder, and a step ST7 oftransferring the substrates to an assembling stage.

Referring to FIG. 2, a method of manufacturing an LCD panel according toanother conventional art includes a step of cutting the integratedparent substrates using a diamond scriber, a step of filling the liquidcrystal between the integrated substrates, a step of sealing a liquidcrystal introducing inlet of the integrated substrates, a step ofgrinding a cut surface of the substrates using a grinder, a step ofattaching the polarizing plates at outer surfaces of the integratedsubstrates, and a step ST7 of transferring the substrates to anassembling stage.

Regarding methods of manufacturing the LCD panel according to theconventional art, at the grinding step, one of the integrated substratesis cut along cutting lines C1, C2 and G1, and then has been grinded at apredetermined angle at the corner of cut surfaces thereof, as shown inFIGS. 3 and 4. In FIGS. 3 and 4, a reference numeral 14 denotes a shortbar connecting gate lines 12 with each other and a reference numeral 16indicates a short bar connecting data lines with each other. The shortbars 14 and 16 discharge the static electricity generated while cuttingthe substrates.

The grinding step removes glass chips remaining at edges of thesubstrates from the substrates, prevents damage to a printed circuitboard attached to a pad and protects the gate line, the data lines andthe panel from cracking.

According to the method referred in FIG. 1, the glass chips around theedges of the substrates generated during the cutting step cause defectsin attaching the polarizing plates to the substrates. The defect in theattachment of the polarizing plates forces the polarizing plates to bere-attached, which increases a manufacturing cost.

The method in which the substrate is ground before attaching thepolarizing plates as referred in FIG. 2 may remarkably reduce defects inthe polarizing plate attachment. However, the removal of the short bar14 from the substrates cut along the cutting line G1 as shown in FIGS. 3and 4, causes malfunction of the panel's TFTs due to the static chargesdue to a friction during the grinding step.

Referring to FIG. 3 again, the cutting of the parent substrate using thelaser light starts at an outer surface of the substrate. The parentglass substrate can be cut along the cutting lines, but theinterconnection lines 12 formed on an inner surface of the substrate areoccasionally not cut. As shown in FIGS. 5 a and 5 b, even though theparent glass substrate 10 is exactly cut along the cutting lines C1 andC2, the crack generated in the parent glass substrate 10 may not betransferred to the interconnection lines 12 disposed on the innersurface of the substrate and the interconnection lines 12 are notexactly cut.

It is considered that the cutting problems are caused by the ductilityand heat expansion difference of metals used for the interconnectionlines.

Sealant is coated on the inner surface of one substrate in order tointegrate the substrates together.

FIG. 6 is a view showing the sealant coated on the substrate, the liquidcrystal introducing inlet 37, and the cutting line 39 a on the substrateaccording to the present invention. Reference numerals 38 a, 38 b, 39 a,and 39 b respectively denote the cutting line and reference numeral 34indicates the black matrix.

Referring to FIG. 6, a seal line formed on the substrate, except for theliquid crystal introducing inlet is not overlapped with the cuttingline. However, a part of the seal line forming the liquid crystalintroducing inlet extends across the cutting line 39 a. Therefore, sincethe cutting line 39 a near the liquid crystal introducing inlet 37 iscut under a cutting condition different from another cutting lines, itis difficult to cut the integrated substrate into a plurality of panelsby laser. Thus, different cutting conditions for the portion near theliquid crystal introducing inlet and for the rest of the substrate haveto be set up, which complicates the cutting process.

As shown in FIG. 12, in the case that the cutting line 39 a extendsacross a neck portion of the liquid crystal introducing inlet 37, thereis a problem in that when the sealant 56 is supplied to close the liquidcrystal introducing inlet 37, air is introduced through the liquidcrystal introducing inlet 37 into a liquid crystal layer between theintegrated substrate 32.

SUMMARY OF THE INVENTION

The present invention has been made to overcome the above describedproblems of the prior art.

It is an object of the present invention to provide a substrate for aliquid crystal display panel, in which glass chips are prevented frombeing created during a cutting of the substrate.

It is another object of the present invention to provide a liquidcrystal display panel of which substrates are grinded without generatingstatic charges.

It is still an objet of the present invention to provide a method ofmanufacturing a liquid crystal display panel capable of being cut by alaser light, in which a conducting layer formed in an inner surface of asubstrate can be prevented from being cut during the cutting of thesubstrate.

It is still further an object of the present invention to provide amethod of manufacturing a liquid crystal display panel capable of beingcut by a laser light, in which air can be prevented from beingintroduced through a liquid crystal inlet between the substrates of thepanel at a step of sealing the liquid crystal inlet.

To accomplish the above object of the present invention, according to anaspect of the present invention, there is provided a method ofmanufacturing a liquid crystal display panel capable of being cut bylaser, comprising the steps of:

emitting a laser light to cut a substrate along a cutting line indicatedon the substrate; and

attaching a polarizing plate to an outer surface of the substrate.

The method of manufacturing a liquid crystal display panel capable ofbeing cut by laser further comprising a step of grinding edges of a cutsurface of the substrate after the step of attaching the polarizingplate to the outer surface of the substrate.

The step of grinding the edges of the cut surface of the substrate maybe performed after the step of attaching the polarizing plate to theouter surface of the substrate.

The laser light focused on the substrate has an ellipse shape, of whichan apsis line is parallel to the cutting line and a minor line is normalto the cutting line. Therefore, the grinding using the laser light canbe omitted.

A parent substrate for the liquid crystal display panel according to thepresent invention includes a short bar thereon connecting the wire withthe others and has the first and second cutting lines which is spaced ata predetermined distance from and parallel to both side of the shortbar.

According to another aspect of the present invention, there is provideda method of manufacturing a liquid crystal display panel capable ofbeing cut by laser, comprising the steps of:

cutting a panel along a cutting line using laser, the panel being formedin such a manner that a first transparent insulated substrate having athin film transistor and wires and pixel electrodes connected with thethin film transistor on an inner surface thereof is integrated to face asecond transparent insulated substrate having a color filter layer andelectrodes on an inner surface thereof;

introducing liquid crystal in a space between the first and secondtransparent substrates and sealing an inlet for introducing the liquidcrystal;

grinding edges of the first and second cut substrates using laser; and

attaching polarizing plates to each of outer surfaces of the first andsecond substrates.

According to still another aspect of the present invention, there isprovided a liquid crystal display panel capable of being cut by laser,comprising:

a first transparent insulated substrate having a thin film transistorand wires and pixel electrodes connected with the thin film transistoron an inner surface thereof, ends of the wires are positioned at apredetermined position near a cutting line on the first transparentinsulated substrate;

a second transparent insulated substrate having a color filtering layerand electrodes corresponding to the pixel electrodes on an inner surfacethereof; and

sealant which is disposed along edges of one of the first and secondsubstrates to form an inlet for introducing the liquid crystal in aplace in order that the first transparent insulated substrate isintegrated with the second transparent insulated substrate,

wherein the panel is cut along the cutting line.

According to still further aspect of the present intention, there isprovided a substrate capable of being cut by laser comprising:

a substrate having an inner surface and an outer surface with a cuttingline;

a conducting layer which is deposited on the inner surface along acutting line of the inner surface corresponding to the cutting line onthe outer surface of the substrate; and

a buffer layer which is disposed along the cutting line between theinner surface and the conducting layer of the substrate,

wherein the substrate and the buffer layer are separately cut by laserhaving different wavelength and the buffer layer is cracked by theconducting layer.

According to still further aspect of the present invention, there isprovided a liquid crystal display panel capable of being cut by lasercomprising:

a first transparent insulating substrate including thin film transistorsformed on an inner surface and a wire connected with the thin filmtransistors and pixel electrodes;

a second transparent insulating substrate having an inner surfacecorresponding to the first transparent insulating substrate, a colorfilter layer formed on the inner surface, a black matrix andcorresponding electrodes; and

a buffer layer which is disposed between the conducting layer and theinner surface and diffuses a crack generated therein to the conductinglayer vertically,

wherein one of the first and second substrate has a cutting line on anouter surface thereof and the first and second substrates and the bufferlayer are respectively cut by laser having a different wavelength.

The first and second transparent insulating substrates is made of aparent glass substrate which has an area corresponding to a sum of areasof the first and second substrates.

The buffer layer is formed on the inner surface of one of the first andsecond substrates along a cutting line corresponding to the cutting lineformed on the outer surface of one of the first and second substrates,with a predetermined width.

The buffer layer is formed on the inner surfaces of the first and secondtransparent insulating substrates along cutting lines corresponding tothe cutting line on the outer surface, with a predetermined width.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and other advantages of the present invention willbecome more apparent by describing in detail the preferred embodimentthereof with reference to the attached drawings, in which:

FIGS. 1 and 2 respectively are flow charts showing a process ofmanufacturing a liquid crystal display panel according to theconventional art;

FIG. 3 is a schematic plan view of a thin film transistor substrate ofthe liquid crystal display panel according to the conventional art;

FIG. 4 is a detailed view of the thin film transistor substrate, markedin a circle A in FIG. 3;

FIGS. 5 a and 5 b are partially sectional views of the thin filmtransistor substrate, in which FIG. 5 a is a sectional view of the thinfilm transistor substrate, taken along a line C1 and FIG. 5 b is asectional view of the thin film transistor substrate, taken along a lineC2 in FIG. 3;

FIG. 6 is a plan view of a liquid crystal display panel according to anembodiment of the present invention;

FIGS. 7 and 8 are flow charts showing a process of manufacturing theliquid crystal display panel according to the embodiment of the presentinvention;

FIG. 9 is a partially sectional view of a corner of the substrate forthe liquid crystal display panel according to the present invention, inwhich the corner of the substrate is grinded;

FIG. 10 is a schematic plan view of a liquid crystal display panelaccording to another embodiment of the present invention;

FIG. 11 is a schematic plan view of a liquid crystal display panelaccording to still another embodiment of the present invention;

FIG. 12 is an enlarged view of a portion marked in a circle A in FIG. 6;

FIG. 13 is an enlarged view of a portion marked in a circle B in FIG.11;

FIG. 14 is a partial sectional view of a substrate to be cut accordingto still another embodiment of the present invention;

FIG. 15 is a perspective view of a color filter substrate to be cutaccording to still another embodiment of the present invention;

FIG. 16 is a perspective view of a thin film transistor substrate to becut according to still another embodiment of the present invention; and

FIG. 17 is a schematic perspective view of a laser cutter for cuttingsubstrates in FIGS. 14 to 16.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, a method of manufacturing a liquid crystal display panelcapable of being cut by a laser light and a substrate for the liquidcrystal display panel according to the present invention will bedescribed in detail with reference to accompanying drawings.

Embodiment 1

FIGS. 7 and 8 are flow charts showing a process of manufacturing aliquid crystal display panel according to the embodiment of the presentinvention.

Referring to FIG. 7, an integrated substrate is provided at a step ST71.The integrated substrate is comprised of a parent glass substrate for athin film transistor substrate (hereinafter, referred to as TFTsubstrate) having an area corresponding to an area of at least one paneland a parent glass substrate for a color filer.

The parent glass substrate for the TFT substrate includes a plurality ofgate lines, a plurality of data lines formed to intersect with the gatelines, thin film transistors and pixel electrodes formed at a point thatthe data lines intersects with the gate lines.

The parent glass substrate also has short bars 14 disposed at each endof interconnection lines to be normal to the interconnection lines,connecting the interconnection lines with each other to prevent staticcharges from damaging TFTs on the panel while cutting, as shown in FIGS.3 and 4. Cutting lines C1 and C2 locates parallel to and apart from theshort bar 14 at a predetermined distance.

The parent glass substrate for the color filter substrate has formedthereon color filter layers respectively provided with red, green, andblue, a black matrix, and corresponding electrodes. The black matrixprevents lights of the color filter layers from being mixed and alsoprevents the TFTs from operating in an off line state.

The integrated substrate is cut along the cutting line by laser, at stepST72. The integrated substrates are cut by laser light one substrate andthen the other substrate. The selected substrate is cut from the outersurface to the inner surface.

The substrate has a smooth cut surface, unlike a surface of thesubstrate cut by a diamond blade. Further, glass chips are not generatedwhile grinding the substrate. Accordingly, it is possible to minimizeerrors due to the glass chips when attaching the polarizing plate to theouter surface of the substrate. The interconnection lines are cutsometimes because the glass chips press the interconnection lines duringa process of TCP bonding. However, few glass chips generated whilecutting the substrate prevent the interconnection lines from being cutduring the process of TCP bonding. A corner of the outer surface wherethe cutting operation starts is a portion where a stress isconcentrated. Therefore, the corner of the outer surface on thesubstrate is vulnerable to crack even by a small impact. Cuttingsubstrates by laser does not concentrate the stress on the corner of thesubstrate, which improves a resistance to impact.

After cutting the substrate completely, the liquid crystal is filledbetween the TFT substrate and the color filter substrate, at step ST73.Then, a liquid crystal introducing inlet is sealed at step ST74.

Next, polarizing plates a respectively attached to each outer surface ofthe TFT substrate and the color filter substrate, at step ST75.

After attaching the polarizing plates, the edges of the substrate isground by laser, at step ST76. The grinding by laser prevents staticcharges from generated due to a friction on the substrate, whichprotects the thin film transistors formed on the inner surface of theTFT substrate from damages by the static charges.

After grinding, the liquid crystal display panel (hereinafter, referredto as LCD panel) is carried to an assembly line in order to be assembledwith other element.

In the process of attaching the polarizing plate to the outer surface ofthe substrates according to the embodiment of the present invention, thepolarizing plates are attached to each outer surface of the integratedsubstrates in alight transmitting type LCD panel, but the polarizingplate is attached to only one outer surface of the integrated substratein a light reflecting type LCD panel.

On the other hand, in the above-described embodiment, after attachingthe polarizing plate, the substrate is ground. However, the substratecan be ground before attaching the polarizing plate.

As shown in FIG. 8, it is possible to perform the process of cutting thesubstrate along the cutting lines by using the laser light at step ST82,the process of filling the integrated substrates with the liquid crystalat step ST83, the process of sealing the liquid crystal introducinginlet at step ST84, the process of grinding the corner of the substrateat step ST85, and the process of attaching the polarizing plates to thesubstrates in sequence.

FIG. 9 is a sectional view of the cut surface 92 and the ground surface94 of the substrate 90 which is cut according to the present invention.The surface 94 is ground to be round.

In the first embodiment of the present invention, both the cuttingprocess and the grinding process are performed by laser. While theprocess of cutting the substrate is performed by using the laser light,however, by aligning laser focused on the outer surface of thesubstrate, of which an apsis is parallel and a minor axis is normal tothe cutting line, the process of grinding the corner on the cut surfaceof the substrate can be omitted. Since the laser light with an ellipseshape round the edges of the cut surface, the grinding process is notrequired. In addition, the use of the laser light having the ellipseshape prevents the generation of glass chips on the inner surface of thesubstrate. Therefore, while connecting the end of a tape carrier packageto the interconnection lines of the inner surface of the TFT substrate,the interconnection lines do not suffer from opening defect due to theglass chips.

According to the first embodiment, by eliminating glass chips that maygenerate during the cutting process, the defects in polarizing plateattachments and the short-cut problems of the interconnection lineswhile bonding the tape carrier package can be reduced. Further, sincethe laser grinding of the surface does not generate static charges, thethin film transistor can be safe from the damage by static charges.

Embodiment 2

The use of laser proposed in the first embodiment is effective forcutting the substrate. However, the use of laser according to the firstembodiment is less effective for cutting the interconnection linesformed in the inner surface of the substrate. Therefore, it is requiredto provide a panel of which interconnection lines can be cut smoothlywhile cutting integrated substrates or single substrates.

FIG. 10 is a schematic plan view showing a relation of theinterconnection lines 106 and the cutting lines 108 on the integratedsubstrate for the LCD panel according to the second embodiment of thepresent invention. In FIG. 10, a reference numeral 104 denotes a blackmatrix having a square shape. The black matrix 104 is formed on one ofthe integrated substrates, for example on the color filter substrate, onwhich sealant is disposed to attach the substrates 102 together.

In FIG. 10, the interconnection lines 106, for example the data lines,adjacent to the cutting line 108 have ends spaced apart at apredetermined distance, for example about 1 mm, from the cutting line108. The interconnection lines, for example the gate lines, adjacent tothe cutting line 109 also have ends spaced apart at a predetermineddistance from the cutting lines 109.

Accordingly, even if the integrated substrates 102 are cut by using thelaser light or the diamond cutter along the cutting lines 108 and 109thereon, cutting defects as shown in FIGS. 5A and 5B may not occur inthe substrates 102 because the interconnection lines are not extendedbelow the cutting lines.

In the second embodiment, on the other hand, when the thin filmtransistors are used to switch pixel electrodes, an insulating film or apassivation film is covered on one of the inner surfaces of theintegrated substrates. If the insulating film and the passivation filmextend across the cutting lines 108 and 109, the insulating andpassivation films can not be cut smoothly due to the propertydifferences. Therefore, the insulating and passivation films must beformed within a region defined by the cutting lines 108 and 109 withoutextending below the cutting lines, in order to prevent the rough cut ofthose films.

The short bars 14 and 16 as shown in FIGS. 3 and 4 may be replaced withelectrostatic diodes or protectors preventing the damage of staticcharges, which are formed within the region defined by the cutting lines108 and 109.

When testing the TFT panel, not a bundle of the interconnection linesbut an individual interconnection line is tested by a probe.

FIG. 11 is a view showing the relation of the cutting line 122 a and theliquid crystal introducing inlet 117 of the integrated substrateaccording to the another embodiment of the present invention. Areference numeral 114 denotes the black matrix formed on the innersurface of one of the integrated substrate. Reference numerals 118 a,118 b, 122 a, and 122 b denote the cutting lines.

As shown in FIG. 11, a sealing line for the liquid crystal introducinginlet 117 is positioned within the region defined by the cutting line122 a.

The relation of the liquid crystal inlet 116 and the cutting line 122 aparallel to the liquid crystal inlet 117 will be described withreference to FIG. 13 below.

As shown FIG. 13, the sealing line 116 near the liquid crystalintroducing inlet 117 is formed in a square shape, which includes afirst line 116 a having an opening, a second line 116 b extendingvertically from an end of the first line 116 a and having a firstlength, and a third line 116 c extending from an end of the second line116 b to be parallel to the cutting line 122 a and having a secondlength.

A distance between the third line 116 c and the cutting line 122 apreferably is about 1 mm.

Referring to FIGS. 12 and 13, the sealing line 116 according to theembodiment of the present invention has the second line 116 b. That is,a neck of the liquid crystal inlet is shorter than that of the structureaccording to the conventional art. Accordingly, the third line 116 cextending parallel to the cutting line 122 a remains after the cuttingof the integrated substrate.

The third line 116 c makes air to be introduced into the integratedsubstrates through a path between the sealing agent 126 and the thirdline 116 c when the sealing agent 126 is sucked in the liquid crystalintroducing inlet 117 to seal the liquid crystal introducing inlet 117at the sealing process. Therefore, the path through which the air isintroduced into the integrated substrates is longer than that of theconventional art, which substantially prevents the introduction of air.

The integrated substrates as constructed above are cut by emitting thelaser light along the cutting line and spreading a refrigerant on thesubstrates to generate cracks.

Alternatively, the cutting lines are formed at a predetermined depth onthe substrate using a diamond blade. Then, a small impact on thesubstrates along the cutting line may divide the substrates into aplurality of small-sized panels.

The substrate made of quartz can be used for the embodiment of thepresent invention. In this case, the panel according to the presentinvention can provide the same effect as the panel made of the glasssubstrate.

On the other hand, in the second embodiment of the present invention,the LCD panel is described as that the interconnection lines arepositioned within the region defined by the cutting lines and that thesealing agent is disposed within the region defined by the cuttinglines. However, both the interconnection lines and the liquid crystalintroducing inlet may be located within the region defined by thecutting lines.

In the second embodiment as described above, since the interconnectionlines, the corresponding electrodes, and the liquid crystal introducinginlet are positioned within the region of the substrate defined by thecutting lines, the interconnection lines are protected from rough cutduring the cutting of the substrate.

Further, at the sealing process to enclose the liquid crystalintroducing inlet, the introduction of the air into the liquid crystallayer is minimized to protect the liquid crystal layer.

Moreover, by introducing the laser cutting, the substrates can be cutunder the same cutting condition, which simplifies the processes.

Embodiment 3

The LCD panel proposed in the second embodiment has the interconnectionlines and the liquid crystal introducing inlet positioned within theregion defined by the cutting lines, which requires the LCD panel designchange. However, the LCD panel according to the third embodiment of thepresent invention can prevent an abnormal cutting of the interconnectionlines without changing of the length of the interconnection lines.

FIG. 14 is a partially sectional view of the substrate to be cutaccording to the third embodiment of the present invention.

Referring to FIG. 14, the glass substrate 32 is used as the substrate142 to be cut, in which the conductive interconnection lines, forexample the interconnection lines made from aluminum having a hightoughness is arranged on the inner surface of the substrate 142 so thatends of the interconnection lines extend across the cutting lines. Areference character CL denotes the cutting line of the glass substrate.The substrate 142 is cut from the outer surface 142 b to the conductiveinterconnection lines 146 through the inner surface 142 a thereof.

A buffer layer 144 having a low toughness is disposed between thesubstrate 142 and the conductive interconnection lines 146. The bufferlayer 144 has a predetermined width along the cutting line CL. When thebuffer layer 144 is cracked, the interconnection line 146 is alsocracked together with the buffer layer 144.

FIG. 15 is a perspective view of a color filter substrate to be cutaccording to still another embodiment of the present invention. FIG. 16is a perspective view of a thin film transistor substrate to be cutaccording to still another embodiment of the present invention.

Referring to FIG. 15, the color filter substrate 150 made from the glasssubstrate is provided as an object to be cut in which the color filterlayer 154 having the red, green, and blue colors is formed on the innersurface 152 a of the glass substrate 152. The corresponding electrodes(not shown) are disposed on the color filter layer 154 of the colorfilter substrate 150.

Since the corresponding electrodes lies along the cutting line 156, thecorresponding electrodes may not be cut precisely. Therefore, a bufferlayer 158 of a predetermined width is disposed along the cutting linebetween the inner surface 152 a of the substrate 152 and thecorresponding electrodes.

The buffer layer 158 is made of metal having the low toughness asdescribed above. Preferably, the buffer layer 158 is made of the samematerial as the black matrix layer (not shown) in the same process. Inthe third embodiment of the present invention, the black matrix layerand the buffer layer 158 are made of chromium (Cr).

Referring to FIG. 16, the TFT substrate 160 containing the gate lines164, source lines 166, pixel electrodes 168, and thin film transistors170 formed on the inner surface 162 a of the glass substrate 162 is tobe cut.

When the gate lines 164 and the source line 166 of the TFT 160 extend tothe cutting line 174, as described above, the abnormal cutting of thesubstrate may be performed. Therefore, the buffer layer 172 having thelow toughness is disposed along the cutting line between extensions ofthe interconnection lines and the inner surface 162 a of the glasssubstrate 162.

The embodiment shown in FIGS. 14 to 16 can be cut using a laser cuttershown in FIG. 17, without defects in cutting the interconnection lines.

Referring to FIG. 17, the cutter is a device capable of cutting thesubstrate using the laser lights respectively having wavelengths w1 andw2. The laser light having the wavelength w1 (hereinafter, referred toas a first laser light) is used for generating the crack on the glasssubstrates 142, 152, and 162, and the laser light having the wavelengthw2 (hereinafter, referred to as a second laser light) is used forgenerating the crack on the buffer layers 144, 158, and 172.

A laser whose wavelength is 10.6 μm with an output of 50˜250 w, such asa yag laser, CO₂ laser, gallium-arsenide laser and ruby laser can beused for those purposes.

The process of cutting the color filter substrate 150 and the TFTsubstrate 160 integrated together using the cutter of FIG. 17 will bedescribed.

The integrated substrate is laid on a plate of the cutter 200. The outersurface of the color filter substrate 150 is facing the cutter 200.

A first laser light emitter 202 of the cutter 200 emits the first laserlight having the wavelength w1 focusing the cutting line 156 of thecolor filter substrate 150 and concentrating on the glass substrate 152.A second laser light emitter 204 adjacent to the first laser lightemitter 202 emits the second laser light having the wavelength w2, whichin turn is transmitted through the glass substrate 152 and focused onthe buffer layer 158.

The glass substrate 152 and the buffer layer 158 are heated by the firstand second laser light, which expand along the cutting line 156 in partand have the stress concentrated on the cutting line thereon.

A refrigerant spreading unit 206 following the second laser emitter 204sprays a refrigerant at an interval of 0.1˜0.3 second on the cuttingline on which the stress is concentrated. Therefore, the glass substrate152 and the buffer 158 which are heated by the laser lights are rapidlycooled.

The cutting lines of the glass substrate 152 and the buffer 158 areexpanded and contracted by heat and refrigerant, so that the high stressis generated along the cutting lines.

When the stress is a larger than a combination force of glass molecules,the amorphous glass molecule structure is broken and the surface of theglass substrate 152 starts to crack.

At this time, a direction of the crack's creation and progression is thesame as that of the laser radiation. That is, the crack is progressedfrom the outer surface to the inner surface of the glass substrate 152,resulting in that the glass substrate 152 is cut thoroughly.

On the other hand, the buffer layer 158 has a stress thereon due to theexpansion and contraction by the second laser light and the refrigerantapplied on the buffer layer 158.

When the stress is larger than a combination force of chromium atoms, acrystal structure of the buffer layer 158 is broken, resulting that acrack is created on the surface of the buffer layer 158.

At this time, the crack is spread into the interconnection lines, whichcut the corresponding electrodes on the edges of the interconnectionlines smoothly along the cutting line of the glass substrate 152.

As described above, after cutting the color filter substrate 150completely, the integrated substrate is flipped over such that the outersurface of the TFT substrate is facing the laser cutter 200 and cut insuch a manner as described above.

The color filter substrate 150 and the TFT substrate 160 used in thepresent embodiment are made of the same glass substrate and the samebuffer layer. The first and second laser emitters for cutting the colorfilter substrate 150 can be used for cutting the TFT substrate withoutchanging laser emitters.

On the other hand, the materials for the buffer layers of the colorfilter substrate and the TFT substrate may be different, depending onthe material for the corresponding electrodes of the color filtersubstrate and the material for the interconnection lines of the TFTsubstrate. In such a case, when the color filter substrate is cut firstand then the TFT substrate is cut, the buffer layer of the TFT substratemay not be smoothly cut. To solve this problem, the cutter shown in FIG.17 may include another laser emitter capable of emitting a laser lighthaving a third wavelength different from the first and second laserlights.

Regarding the above embodiment, while the substrate having a sizecorresponding to the panel size has been described, the laser cutteraccording to the present invention is suitable to cut the parent glasssubstrate having an area corresponding to a total area of at least twopanels in order to improve the productivity.

In the above-described embodiment, although the laser cutter has beendescribed to emit the first laser light so as to create the crack on theglass substrate and then to emit the second laser light so as to createthe crack on the buffer layer, the laser cutter may emit the secondlaser light first and then the first laser light to cut the substrate.

According to the third embodiment of the present invention, when the LCDpanel or the integrated glass substrate having the conductiveinterconnection lines thereon is cut by the laser cutter, by laying abuffer layer of low toughness and having a property of transferring thecrack rapidly between the conductive interconnection lines and the glasssubstrate, the conductive interconnection lines can be smoothly cut.

While the present invention has been particularly shown and describedwith reference to a particular embodiment thereof, it will be understoodby those skilled in the art that various changes in form and detail maybe effected therein without departing from the scope of the invention asdefined by the appended claims.

1-5. (canceled)
 6. A method for cutting a liquid crystal display (LCD)panel having a shorting bar, the method comprising steps of: irradiatinga CO₂ laser light onto the LCD panel along a first cutting line, thefirst cutting line being in substantially parallel with the shorting baroutside of the shorting bar; and irradiating the CO₂ laser light ontothe LCD panel along a second cutting line, the second cutting line beingin substantially parallel with the shorting bar inside of the shortingbar.
 7. The method of claim 6, further comprising a step of irradiatingthe CO₂ laser light onto a corner of the LCD panel to round the cornerof the LCD.
 8. The method of claim 6, further comprising a step ofcooling the LCD panel onto which the CO₂ laser light is irradiated.
 9. Amethod for manufacturing a liquid crystal display (LCD) panel, themethod comprising steps of: irradiating a first laser light onto a thinfilm transistor (TFT) parent substrate along a TFT cutting line to forma TFT substrate; irradiating a second laser light onto a color filterparent substrate along a color filter cutting line to form a colorfilter substrate; and combining the TFT substrate and the color filtersubstrate.
 10. The method of claim 9, wherein the first laser light andsecond laser light are a CO₂ laser light.
 11. The method of claim 9,further comprising steps of: irradiating a first YAG laser light ontothe TFT parent substrate; and irradiating a second YAG laser light ontothe color filter parent substrate.
 12. The method of claim 9, furthercomprising steps of: irradiating the CO₂ laser light onto a corner ofthe TFT substrate to round the corner of the TFT substrate. irradiatingthe CO₂ laser light onto a corner of the color filter substrate to roundthe corner of the color filter substrate.
 13. A method for cutting athin film transistor (TFT) parent substrate, the method comprising astep of irradiating a CO₂ laser light having an elliptical cross-sectiononto the TFT parent substrate along a TFT cutting line to form a TFTsubstrate.
 14. The method of claim 14, further comprising a step ofirradiating the CO₂ laser light onto a corner of the TFT substrate toround the corner of the TFT substrate.
 15. The method of claim 14,further comprising a step of irradiating a YAG laser light onto the TFTparent substrate prior to the step of irradiating the CO₂ laser light.16. The method of claim 13, further comprising a step of cooling the TFTparent substrate onto which the CO₂ laser light is irradiated.
 17. Amethod for cutting a color filter parent substrate, the methodcomprising a step of irradiating a CO₂ laser light having an ellipticalcross-section onto the color filter parent substrate along a colorfilter cutting line to form a color filter substrate.
 18. The method ofclaim 17, further comprising a step of irradiating the CO₂ laser lightonto a corner of the color filter substrate to round the corner of thecolor filter substrate.
 19. The method of claim 18, further comprising astep of irradiating a YAG laser light onto the color filter parentsubstrate prior to the step of irradiating the CO₂ laser light.
 20. Themethod of claim 19, further comprising a step of cooling the colorfilter parent substrate onto which the CO₂ laser light is irradiated.